BEGIN;
BEGIN
EXPLAIN (ANALYZE, BUFFERS)
select
	cntrycode,
	count(*) as numcust,
	sum(c_acctbal) as totacctbal
from
	(
		select
			substr(c_phone, 1, 2) as cntrycode,
			c_acctbal
		from
			customer
		where
			substr(c_phone, 1, 2) in
				('28', '25', '14', '22', '20', '23', '33')
			and c_acctbal > (
				select
					avg(c_acctbal)
				from
					customer
				where
					c_acctbal > 0.00
					and substr(c_phone, 1, 2) in
						('28', '25', '14', '22', '20', '23', '33')
			)
			and not exists (
				select
					*
				from
					orders
				where
					o_custkey = c_custkey
			)
	) as vip
group by
	cntrycode
order by
	cntrycode;
                                                                              QUERY PLAN                                                                              
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
 Sort  (cost=692846.67..692846.68 rows=3 width=20) (actual time=16390.493..16390.494 rows=7 loops=1)
   Sort Key: (substr((public.customer.c_phone)::text, 1, 2))
   Sort Method: quicksort  Memory: 25kB
   Buffers: shared hit=249436 read=77170 dirtied=294 written=5022
   InitPlan 1 (returns $0)
     ->  Aggregate  (cost=52842.25..52842.26 rows=1 width=4) (actual time=688.858..688.858 rows=1 loops=1)
           Buffers: shared hit=35286 read=1057 written=139
           ->  Bitmap Heap Scan on customer  (cost=6632.66..51891.67 rows=380229 width=4) (actual time=146.970..567.615 rows=381653 loops=1)
                 Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{28,25,14,22,20,23,33}'::text[])) AND (c_acctbal > 0::double precision))
                 Buffers: shared hit=35286 read=1057 written=139
                 ->  Bitmap Index Scan on customer_c_phone_idx_c_acctbal  (cost=0.00..6537.61 rows=380229 width=0) (actual time=134.686..134.686 rows=381653 loops=1)
                       Index Cond: (substr((c_phone)::text, 1, 2) = ANY ('{28,25,14,22,20,23,33}'::text[]))
                       Buffers: shared hit=8 read=1057 written=139
   ->  HashAggregate  (cost=640004.35..640004.39 rows=3 width=20) (actual time=16390.414..16390.417 rows=7 loops=1)
         Buffers: shared hit=249434 read=77170 dirtied=294 written=5022
         ->  Hash Anti Join  (cost=596623.17..639560.80 rows=59140 width=20) (actual time=15328.467..16351.314 rows=63539 loops=1)
               Hash Cond: (public.customer.c_custkey = orders.o_custkey)
               Buffers: shared hit=249434 read=77170 dirtied=294 written=5022
               ->  Bitmap Heap Scan on customer  (cost=2903.47..41842.51 rows=139468 width=24) (actual time=818.499..1438.138 rows=190806 loops=1)
                     Recheck Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{28,25,14,22,20,23,33}'::text[])) AND (c_acctbal > $0))
                     Buffers: shared hit=37466 read=34601 written=387
                     ->  Bitmap Index Scan on customer_c_phone_idx  (cost=0.00..2868.61 rows=139468 width=0) (actual time=794.261..794.261 rows=190806 loops=1)
                           Index Cond: ((substr((c_phone)::text, 1, 2) = ANY ('{28,25,14,22,20,23,33}'::text[])) AND (c_acctbal > $0))
                           Buffers: shared hit=35296 read=1596 written=193
               ->  Hash  (cost=405283.20..405283.20 rows=15074920 width=4) (actual time=14491.572..14491.572 rows=15000000 loops=1)
                     Buckets: 2097152  Batches: 1  Memory Usage: 527344kB
                     Buffers: shared hit=211965 read=42569 dirtied=294 written=4635
                     ->  Seq Scan on orders  (cost=0.00..405283.20 rows=15074920 width=4) (actual time=0.041..6101.794 rows=15000000 loops=1)
                           Buffers: shared hit=211965 read=42569 dirtied=294 written=4635
 Total runtime: 16543.071 ms
(30 rows)

COMMIT;
COMMIT